envelope Contact 

SAVE THE DATE for the 18th IATSO Conference

Poznan, Poland


If you are interested in becoming a IATSO Member

please have a look onto IATSO´s statutes to see whether you fulfill the requirements for IATSO membership

Read morechevron

To access the member-restricted area of this website

login herechevron

Join us at IATSO 2023

in Poznan, Poland, from August 26th - August 28th, 2025

register herechevron

Give us input

Abstract Submission - IATSO 2025


Effective treatment for those who have engaged in sexually inappropriate behavior

Liam E. Marshall


A recent evaluation of the Rockwood treatment program for adult males who have engaged in sexual offending found our participants to have a statistically significantly lower rate of reoffending than did two groups matched for risk and time-at-risk, namely a Treatment As Usual and Untreated group (Olver et al., 2020). This statistically significant reduction in reoffending was also found for violent offending. In a subsequent report (Marshall & Marshall, 2021), we evaluated the costs versus benefits of providing this treatment in the Canadian federal prison system and found, besides less victimization, significant savings to the public. These results and the treatment program approach, content, and delivery (Marshall et al., 2011) will be described and discussed. 


Selected Abstract References (omitted from text): 

Marshall, W. L., & Marshall, L. E. (2021). A cost–benefit analysis of a treatment program for adult males who have offended sexually, Journal of Sexual Aggression. DOI: 10.1080/13552600.2021.1934133

Olver, M. E., Marshall, L. E., Marshall, W. L., & Nicholaichuk, T. P. (2020). A Long-Term Outcome Assessment of the Effects on Subsequent Reoffense Rates of a Prison-Based CBT/RNR Sex Offender Treatment Program with Strength-Based Elements. Sexual Abuse, 32, 127-153. DOI: 10.1177/1079063218807486

Marshall, W.L., Marshall, L.E., Serran, G.A., & O’Brien, M. D. (2011). Rehabilitating Sexual Offenders: A Strength-Based Approach. Washington, DC: American Psychological Association


Liam Marshall, Ph.D., RP, ATSAF received his Doctoral and other degrees in Psychology from Queen’s University in Kingston, Canada. He has been providing treatment and conducting research on offenders and offenders with mental health issues for more than 25 years. Liam has more than 100 peer- reviewed publications and is co-author/co-editor of four books. He is a board member and reviewer for many international journals, and has made numerous international conference presentations on offender and mental health issues. He has provided consultation to governments and delivered trainings for therapists and staff working with offenders in 28 countries. Liam has been named a Fellow of the Association for the Treatment of Sexual Abusers (ATSA). He is currently Director of Rockwood Psychotherapy & Consulting and an Assistant Professor in the Department of Forensic Psychiatry at the University of Toronto.